The objective of this research effort is a continuation of our studies of persistent poliovirus infections of the central nervous system (CNS) of mice. Our prior studies have demonstrated that poliovirus can persist in the CNS of immunosuppressed mice and then cause late paralysis. We plan to further study the mechanisms by which the lytic poliovirus can persist by investigations into the pathogenesis of the infection, the immunologic parameters, and the events at the molecular level. These studies will concentrate on the three main areas of investigation: (1) viral dissemination, (2) the immune response to infection, and (3) the molecular correlates of persistence and paralysis. The study of viral dissemination will employ axonal transport inhibitions, viral assays, and post-embedding immunoperoxidase staining to follow the spread of infection. The use of the fast axonal transport inhibitor colchicine has revealed that the virulent Lansing strain is spread via fast axonal transport. Studies using immunoperoxidase staining and viral assay to follow infection will be started in the coming year. The role of humoral and cellular immunity in CNS viral clearance and persistence is being analyzed by infection of anti-u or antithymocyte sera-treated mice and of B-cell deficient (CBA/N) or T-cell deficient (Nude) mice. Analysis of the humoral immunity will also determine the T-cell dependency or independency of the response. A lymphocyte transformation assay has been established and will be used to analyze cellular immunity during the course of the infection. Studies of the molecular correlates of persistence included 2-dimensional polyacrylamide gel electrophoresis of viral proteins from isolates obtained during the persistent infection. We have been unable to detect any electrophoretic changes in these viral proteins. Also, the previously observed new RNase T1-resistant oligonucleotides seen during the persistent infection will be mapped on the viral genome. Purified, labeled poliovirus RNA will be digested with RNase III. The poly (A) containing generated oligonucleotides will be absorbed to oligo (dT) column, eluted, and separated in SDS-agarose-acrylamide gels. Oligonucleotides will be detected by autoradiography, cut out, extracted, digested with RNase T1 and fingerprinted.